Junctions are disrupted in replicative senescent HUVECs. (a) Immunofluorescent labeling of junction proteins in senescent and non-senescent HUVECs. The corresponding DAPI staining of senescent HUVECs labeled for occludin and claudin-5 are shown (bar 25 μm). (b) Western blot analysis of junction protein expression levels in non-senescent and senescent HUVECs. Tubulin was used as a loading control. (c) Quantitative analysis of Western Blots of three independent experiments as performed in (b).